Gentamicin and montelukast cannot be taken together. Gentamicin is an antibacterial drug, and oral gentamicin can be used to treat bacterial diarrhea. Montelukast is an antidiarrheal drug. Montelukast is used to inhibit diarrhea by absorbing water from the intestines and forming a protective film in the gastrointestinal tract to adsorb harmful bacteria and toxins produced by the harmful bacteria, thus inhibiting diarrhea. If gentamicin and montelukast are taken together, most of the gentamicin will be isolated outside the intestinal wall and cannot reach the site of action, and a large part of the gentamicin will be adsorbed by the montelukast and will not be able to have a therapeutic effect. Therefore, when gentamicin and montelukast must be taken together, it is recommended that gentamicin be taken first, followed by montelukast after an interval of 2-4 hours.